Engines fueled with ethanol have proven difficult to start at temperatures less than about 25.degree. C. because at low temperatures ethanol does not produce sufficient vapor to support combustion. The current practice for starting ethanol fueled engines at low temperatures is to discharge a quantity of gasoline into the engine induction system; a fraction of the gasoline evaporates sufficiently to start the engine, and the subsequent increase in engine temperature is sufficient to run the engine on ethanol.
The system in current use requires the operator to prime the engine with a quantity of gasoline before starting the engine. To start and sustain operation of the engine, the operator must estimate the quantity of gasoline which should be added before the engine is started. If the operator does not add sufficient gasoline, the engine may start but subsequently stall as the engine throttle is opened. If the operator adds excess gasoline, the engine may operate satisfactorily, but the excess gasoline will be wasted.